In recent years, centrifugal microfluidic or lab-on-a-disc (LOAD) system which aims at integrating tedious benchtop assays into one chip plays a more and more important role in point-of-care diagnostics, drug discovery and food analysis. However, on one hand, as the direction of the centrifugal force on the chip is always radially outward, the freedom of fluid manipulation in the LOAD system is limited. Besides, because the radius limitations and the flow direction are always away from the rotation center, large-scale assays integration on the disc-shaped chip is also difficult.
To add a new degree of freedom for fluidic manipulation, many systems have been developed in centrifugal microfluidic field. These systems comprise multi-manipulation strategies induced LOAD platforms such as active pressure pump or optical manipulation induced LOAD systems, chip orientation changeable LOAD system such as speed actuated inertial mechanical structure induced LOAD system or articulated centrifugal platform and so on. However, almost all these methods make the system more expensive and complicated, which increases the market entry barrier and increases the difficulty of point-of-care. Furthermore, the rotation system in the LOAD system is cumbersome compared with the disc-shaped chip, which sacrifices the portability of LOAD systems. Also, there is no unified specification in the design of these rotation systems, which also increases the market entry barrier.
To solve these problems, a lab-tube system and a lab on DVDs system have been suggested, which are more universal and portable. However, these lab-tube or lab on DVDs systems limited the freedom of the fluidic manipulation, which in turn increases the difficulty of implementation of bioassays in this system.